Enhanced electrochemical reduction of hydrogen peroxide at metallic electrodes modified with surfactant and salt

The enhanced electrocatalytic reduction of hydrogen peroxide brought about by the modification of noble metal electrode surfaces with a modification of surfactant and salt was assessed. A range of electrodes composed of Ag, Au and Pt, either as continuous metal films or as particulate metallic pastes were employed. Several surfactants (cationic, anionic and non-ionic), as well as a range of Group I metal halides with differing cations were all investigated to assess the contribution of these components to the reduction of hydrogen peroxide at −0.1 V vs. Ag/AgCl. It was shown that on silver paste electrodes, all surfactant/salt combinations enhanced the observed catalysis. However, the degree to which they did this appears related to the critical micellar concentration of the surfactant, the size of the Group I metal ion and the optimum formation of lamellar structures formed by the surfactant/salt combination. Metallic electrodes showed less enhancement of catalysis over particulate paste electrodes. In addition, higher grade metallic surfaces showed poorer enhancements in catalysis which may relate to the extent of surface defects amenable to surface modification, as observed by electron microscopy. Silver paste electrodes modified with dodecylbenzene sulphonic acid/KCl exhibited a catalytic rate of 5.47 × 10−2 AM−1 cm−2, which was between 2- and 4-fold less than that observed on equivalent Pt electrodes.